diff --git a/src/calibre/headless/headless_integration.h b/src/calibre/headless/headless_integration.h
index 5d32f363a9..5c1316639b 100644
--- a/src/calibre/headless/headless_integration.h
+++ b/src/calibre/headless/headless_integration.h
@@ -36,13 +36,13 @@ public:
     explicit HeadlessIntegration(const QStringList &parameters);
     ~HeadlessIntegration();
 
-    bool hasCapability(QPlatformIntegration::Capability cap) const;
-    QPlatformFontDatabase *fontDatabase() const;
+    bool hasCapability(QPlatformIntegration::Capability cap) const override;
+    QPlatformFontDatabase *fontDatabase() const override;
 
-    QPlatformWindow *createPlatformWindow(QWindow *window) const;
-    QPlatformBackingStore *createPlatformBackingStore(QWindow *window) const;
-    QAbstractEventDispatcher *createEventDispatcher() const;
-    QPlatformOpenGLContext *createPlatformOpenGLContext(QOpenGLContext *context) const;
+    QPlatformWindow *createPlatformWindow(QWindow *window) const override;
+    QPlatformBackingStore *createPlatformBackingStore(QWindow *window) const override;
+    QAbstractEventDispatcher *createEventDispatcher() const override;
+    QPlatformOpenGLContext *createPlatformOpenGLContext(QOpenGLContext *context) const override;
 	QStringList themeNames() const override;
 	QPlatformTheme *createPlatformTheme(const QString &name) const override;
 
@@ -50,7 +50,7 @@ public:
 
     static HeadlessIntegration *instance();
 
-    virtual QPlatformServices *services() const { return platform_services.data(); }
+    virtual QPlatformServices *services() const override { return platform_services.data(); }
 
 private:
     QScopedPointer<QPlatformFontDatabase> m_fontDatabase;